1. Field of the Invention
The invention relates to a thyristor with a common-anode main and auxiliary thyristor integrated in a wafer-like semiconductor chip with at least four alternating zones of different conductivity types.
2. Description of the Prior Art
In a known thyristor, a first control electrode, with a first control terminal lead brought out through the thyristor case, contacts a small-area control zone recessed in the emitter zone. Disposed in this recess and around the small-area contact is a first ring zone which is at least as highly n-doped as the emitter zone and which is partially contacted, as also is a portion of a p-doped base zone emerging at various places on the chip surface in forming a shorted auxiliary emitter, by a second control electrode intended for the auxiliary thyristor (amplifying gate), which is provided with a second control terminal lead brought out through the thyristor case and which is further provided with a control device for the same. This thyristor, as described above, is used as a power thyristor with appropriate field of application, e.g. for a rectifier-fed supply, in which parallel-connected thyristors are used.
Such a known type of power thyristor, to improve its control characteristics, has distributed over its surface slave control electrodes driven from the amplifying gate over blocking-layer-free conducting paths (DT-OS No. 21 46 178). An external connection to these conducting paths, herein called a second control terminal, is provided in the known case. For control of several parallel-connected power thyristors, control power must be supplied, which increases with the number of parallel-connected thyristors. The known power thyristor as well as the usual power thyristor of today possess a gate arrangement with internal firing or control current amplification, the aforementioned amplifying gate (e.g. U.S. Pat. Nos. 3,476,989; 3,579,060; 3,590,346 and General Electric Publication 671.15, 3/1969 "The Amplifying Gate SCR"). Amplifying gate thyristors however generally have longer turn-on times than thyristors with the "normal" control zone-control electrode arrangement (normal gate). In the first mentioned known case the thyristor is triggered via the first control terminal with propagation of the firing process through the amplifying gate and the slave control electrodes which provide for a uniform firing process distributed over the thyristor surface.
The arrangement of adjacent differently doped and sometimes highly doped ring zones, contacted by a control electrode with an external control terminal, is straight-forward in a thyristor with integrated auxiliary thyristor (DT-OS No. 15 89 455). In the known case, however, there is an external connection to discrete components in order to obtain simultaneous initiation of the firing process in the auxiliary thyristor(s) and the main thyristor.